The present invention relates to a safety belt reeling or winding device having a tensioning mechanism that acts on a belt winding shaft and that is provided with a drive means, wherein upon initiation the tensioning mechanism is adapted to be coupled via a tensioner coupling with the belt winding shaft. The belt winding device is furthermore provided with a force-limiting device for a predetermined belt withdrawal, wherein the connection between the belt winding shaft and the tensioning mechanism is adapted to be eliminated after conclusion of a tensioning movement acting in a winding direction of the belt. The tensioning mechanism has a driving cable that is adapted to be unwound from a cable pulley that is adapted to be coupled to the belt winding shaft.
Such a belt winding device can be embodied not only as a self-blocking belt winding device that is equipped with a blocking device that is activated in a vehicle-sensitive and/or belt-sensitive manner, but also as a so-called end or limit fitting tensioner that tensions components held on the belt and after conclusion of the tensioning process fixes the position thereof.
The safety belt winding device of the aforementioned general type and embodied as a self-blocking belt winding device is disclosed in U.S. Pat. No. 5,522,564. To the extent that the known safety belt winding device has a force-limiting device, after conclusion of the tensioning process, accompanied by the absorption of energy, the force-limiting device permits a limited movement of the strapped-in passenger in order to dampen belt forces that act upon the body of the passenger. To the extent that in this connection a rotation of the belt winding shaft in the belt withdrawal direction occurs, this rotation returns the drive apparatus of the tensioning device to its starting position. If in this connection there is not available sufficient length of the cable of the tensioning device, the force-limiting device, i.e. the predetermined movement, cannot be fully utilized. Therefore, the known safety belt winding device already provides for elimination of the connection between the belt winding shaft and the tensioning device upon conclusion of the tensioning movement, so that a reverse rotation of the belt winding shaft in the belt withdrawal direction counter to the tension direction is possible over a greater path. For this purpose, U.S. Pat. No. 5,522,564 describes various proposals such as cutting the driving cable or uncoupling the cable pulley from the belt winding shaft.
It is an object of the present invention, for a safety belt winding device having the aforementioned features, to provide for a straightforward and reliably operating separation of the belt winding shaft from the tensioning mechanism.